How to Verify Shelf Clearance Before Ordering Grow Bars
A practical rack clearance budget for fixture bodies, brackets, connectors, crop height and layout evidence.
Before ordering grow bars for a multi-tier rack, measure the usable shelf space and the full installed fixture envelope. Compare those dimensions with the crop, tray and maintenance space required at the tallest expected crop stage. A fixture body fitting on paper does not establish clearance for its brackets, cable bends or connectors, and it does not prove the light level at the canopy.
Start with the actual rack
Record the clear inside length and width between posts, braces and shelf lips at the intended mounting position. Measure from the growing surface to the lowest obstruction above it, not just the nominal outside rack height. Identify rails, irrigation lines and removable trays that could interfere with installation or access.
Build a vertical clearance budget
For each tier, subtract the installed fixture drop below the upper shelf, tray or container height, and expected maximum crop height from the measured clear tier height. The remainder is the available fixture-to-canopy gap. Keep dimensions in the same units and record the measurement reference points. This is a geometry check, not a recommended mounting distance or a safety clearance.
Example: if a tier has 400 mm clear height, an installed assembly drops 60 mm, the tray is 50 mm high and the maximum canopy is 180 mm above the tray, the remaining gap is 110 mm. These are illustrative project measurements, not Number product dimensions or a recommended gap. Confirm the crop and layout requirements separately.
Check the full installed envelope
Number’s current product records list the LED PGF18 body as 1195 × 32 × 32 mm (length × width × height), and the LEDtb F75 as 1147 × 50 × 50 mm. These are listed body dimensions; obtain the drawing for the exact ordered configuration and confirm how brackets, connectors and cable bends change the installed envelope before using either figure for final fit approval.
Review the LED PGF18 product details
Review the LEDtb F75 product details
Ask the supplier for the mounting drawing, bracket positions, connector projection, cable routing and service access for the selected configuration. Verify fastener compatibility and rack load capacity with the rack provider and installer. Do not assume a generic cable bend radius or clearance requirement; obtain the applicable instructions for the actual assembly.
Separate physical fit from lighting performance
A positive clearance budget only shows that the proposed dimensions leave a gap. Ask for a layout or measurement plan at the intended canopy heights, including fixture positions and PPFD measurement points. Account for crop growth and operational access; revisit the layout if the rack, fixture configuration or growing method changes. PPF is a fixture output measure and does not by itself specify the light reaching a particular canopy.
Release the order with an evidence sheet
Record the rack revision, measured clear tier dimensions, tray and maximum crop heights, fixture model and revision, mounting drawing, connector and cable envelope, calculated remaining gap, layout assumptions and the person responsible for each open item. Mark unknown dimensions as pending rather than zero. Have the installer and cultivation team resolve the pending items before order approval.
Send the rack dimensions and proposed growing arrangement to Number for a project discussion.